A, No they aren’t. Eevee isn’t capable of producing accurate enough global illumination, so it relies on ambient occlusion for contact shadows. That’s exactly what I am seeing on that Cycles render.
B, Yes, by today’s standards of lighting quality it’s considered low quality.
I am talking about the lighting quality, not the other aspects, such as modeling or texturing work. They are actually on good level, which makes the lacking lighting quality that much more apparent.
C, No, the final workflow isn’t much helpful, if you have to switch 10 different knobs every time you jump between preview quality and final quality. All the more problems arise when you are not working in the conditions of final image. We should be pushing towards interactivity and WYSIWYG workflows, not away from them. Having different settings for previews and finals is legacy workflow that should die as soon as possible.
On top of that, there ARE solutions which can make Cycles several times faster, and at the same time actually increase the resulting quality of the artwork by allowing artists to use more realistic amount of indirect light bounces without worrying about destroying performance. More on that here: Cycles Performance
But I still strongly believe that achieving that by regressing back to ancient primitive methods like constant ambient light with small, strong ambient occlusion shadows is not a way to go about it. It generally causes users to produce lower quality work while taking even more time to do so.